Since the beginning of antiquity, both pharmacy and medicine have sought a dosage form for the controlled administration of a beneficial drug. The first written reference to a dosage form is in the Eber Papyrus written about 1552 B.C. The Eber Papyrus mentioned dosage forms such as anal suppositories, vaginal pessaries, ointments, oral pill formulations and other dosage preparations. About 2500 years passed without any advance in dosage form development until the Arab physician Rhazes, 863-925 A.D., invented the coated pill. About a century later the Persian Avicenna, 980-1037 A.D., coated pills with gold or silver for increasing patient acceptability and for enhancing the effectiveness of the drug. Also, around this time, the first tablet was described in Arabian manuscripts written by Al-Zahrawi, 936-1009 A.D. The manuscripts described a tablet formed from the hollow impressions in two matched-facing tablet molds. Pharmacy and medicine waited about 800 years for the next innovation in dosage forms when in 1833 Mothes invented the soft gelatin capsule for administering a drug. Fifteen years later, in 1848 Murdock invented the two-piece hard gelatin capsule. The coating of pills with tolu was first recommended about 1860, and in 1884 Unna introduced enteric coating with Keratin coated pills.
The technical valve of sustained released dosage forms was recognized by Lipowski who, in 1938, discussed the desirability of a slow and constant supply of a drug to an organism. Lipowski's patents were the first to describe an oral dosage for consisting of a number of small drug containing beads, having different thickness of coating, utilized to give a slow and constant release of drug on ingestion. In 1952 Blythe conceived of the use of multiple small pellets which could be coated and which, independent of pH, would have reproducible release rates and prolonged drug release. Blythe uses varying coating thicknesses of time-delay materials in a single capsule.
The next quantum and profound advancement in dosage forms came in 1972 with the invention of the osmotic delivery system by inventors Theeuwes and Higuchi. This unique osmotic dosage form is manufactured in one embodiment for oral use, and in this embodiment it embraces the appearance of a tablet with at least one delivery portal. The delivery portal can be preformed or formed by leaching a pore former during operation of the dosage form. It is the first oral dosage form that delivers throughout the entire gastrointestinal tract a known amount of drug per unit time at a controlled rate of delivery. The oral osmotic device maintains its physical and chemical integrity during the prolonged period of time it transits the total length of the gastrointestinal tract.
The above discussed osmotic dosage form represents an outstanding and pioneering advancement in the art and science of drug delivery. Now it has been discovered a need exists for a delivery system that loses its physical and chemical integrity at the end of the delivery period for discharging the dosage form from the environment of use, mainly the gastrointestinal tract. The need exists for a dosage form that loses its structural integrity, that is for a dosage form that becomes compressible and/or self-destructs for avoiding possible retention of the empty dosage form within the gastrointestinal tract.